Poem written in 1791 by Robert Burns.

When first my brave Johnie lad came to this town,
He had a blue bonnet that wanted the crown,
But now he has gotten a hat and a feather -
Hey, brave Johnie lad, cock up your beaver!

Cock up your beaver, and cock it fu' sprush!
We'll over the border and gie them a brush:
There's somebody there we'll teach better behavior -
Hey, brave Johnie lad, cock up your beaver!

For those of you not familiar with Burnsian language, the "beaver" was a kind of furry hat worn in the Highlands at the time. So the poem is about cocking your hat to cheer yourself up. Obviously. What else could it be about?